Yeah, I suspect humanity would be millenia behind where we are technologically IOTL absent horse domestication.
I don't know...
There's no substitute to horses in warfare, that's true.
But in all other spheres people can use donkeys, oxen and camels. And no need for millennium to breed, they are good as they are.
Instead of one horse to pull a cart, you can harness two donkeys, something like that, no big deal.
Speed is crucial for warfare, for real life economic purposes it's not
that essential.
I doubt it; sheer distance would make supporting an army there (and keeping control of any conquests) difficult, and a lot of China's western and southern borders consisted of mountains and forests, very difficult terrain to campaign across.
Bad wording from my part, sorry.
I didn't mean conquering and
keeping. I meant conquering, holding for some time and then loosing it.
But after loosing these parts would stay part of 'Chino-sphere' - the regions under strong Chinese influence, like OTL Corea, Japan, Vietnam etc.
Even in OTL some conquering was possible, I mean the idea of expansion was not alien to the Chinese mentality.
In ATL China would built a lot of grand canals and other infrastructural projects.
Instead of Great Wall(s).
So in the alternative world 'without horses' China is less looted by the nomads, it is less scorched from time to time, it doesn't have to pay much tribute to pay off the nomads, it doesn't have to man the Great Wall(s), it doesn't have to loose too many armies (men, horses and oxen) in the steppes on a regular basis.
So the Chinese economy prosper, there'a a population boom (according to
Malthusian principle) and China might afford spending more it's men on expansion.
And the other difference with OTL might be change in the Chinese mentality. China might become less 'closed', more inclined towards expanding into the outer world.
I mean in OTL sending fleets somewhere far away and spending finances for similar purposes was kind of reckless. Everybody knows that this money and efforts would be
much better used on maintaining the Northern border against the nomads - because just wait and in no time the hordes of mounted warriors would gather and storm China. And then your overseas lunatic ventures won't help you.
In the alternative "world without horses" there's less need to keep an eye on the North and that Chinese attitude might change...